include/lttng/lttng.h

   1 /*
   2  * lttng.h
   3  *
   4  * Linux Trace Toolkit Control Library Header File
   5  *
   6  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #ifndef _LTTNG_H
  24 #define _LTTNG_H
  25
  26 #include <asm/types.h>
  27 #include <sys/types.h>
  28 #include <stdint.h>
  29 #include <limits.h>
  30
  31 /* Default unix group name for tracing. */
  32 #define LTTNG_DEFAULT_TRACING_GROUP "tracing"
  33
  34 /* Environment variable to set session daemon binary path. */
  35 #define LTTNG_SESSIOND_PATH_ENV "LTTNG_SESSIOND_PATH"
  36
  37 /* Default trace output directory name */
  38 #define LTTNG_DEFAULT_TRACE_DIR_NAME "lttng-traces"
  39
  40 /*
  41  * Event symbol length. Copied from LTTng kernel ABI.
  42  */
  43 #define LTTNG_SYMBOL_NAME_LEN 128
  44
  45 /*
  46  * Every lttng_event_* structure both apply to kernel event and user-space
  47  * event.
  48  */
  49
  50 /*
  51  * Domain type are the different possible tracers.
  52  */
  53 enum lttng_domain_type {
  54         LTTNG_DOMAIN_KERNEL                   = 1,
  55         LTTNG_DOMAIN_UST                      = 2,
  56         LTTNG_DOMAIN_UST_EXEC_NAME            = 3,
  57         LTTNG_DOMAIN_UST_PID                  = 4,
  58         LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN  = 5,
  59 };
  60
  61 /*
  62  * Instrumentation type of tracing event.
  63  */
  64 enum lttng_event_type {
  65         LTTNG_EVENT_TRACEPOINT,
  66         LTTNG_EVENT_PROBE,
  67         LTTNG_EVENT_FUNCTION,
  68         LTTNG_EVENT_FUNCTION_ENTRY,
  69 };
  70
  71 /*
  72  * LTTng consumer mode
  73  */
  74 enum lttng_event_output {
  75         LTTNG_EVENT_SPLICE = 0,
  76         LTTNG_EVENT_MMAP   = 1,
  77 };
  78
  79 /* Event context possible type */
  80 enum lttng_event_context_type {
  81         LTTNG_EVENT_CONTEXT_PID                = 0,
  82         LTTNG_EVENT_CONTEXT_PERF_COUNTER       = 1,
  83         LTTNG_EVENT_CONTEXT_COMM               = 2,
  84         LTTNG_EVENT_CONTEXT_PRIO               = 3,
  85         LTTNG_EVENT_CONTEXT_NICE               = 4,
  86         LTTNG_EVENT_CONTEXT_VPID               = 5,
  87         LTTNG_EVENT_CONTEXT_TID                = 6,
  88         LTTNG_EVENT_CONTEXT_VTID               = 7,
  89         LTTNG_EVENT_CONTEXT_PPID               = 8,
  90         LTTNG_EVENT_CONTEXT_VPPID              = 9,
  91 };
  92
  93 enum lttng_calibrate_type {
  94         LTTNG_CALIBRATE_FUNCTION               = 0,
  95 };
  96
  97 struct lttng_domain {
  98         enum lttng_domain_type type;
  99         union {
 100                 pid_t pid;
 101                 char exec_name[NAME_MAX];
 102         } attr;
 103 };
 104
 105 /* Perf counter attributes */
 106 struct lttng_event_perf_counter_ctx {
 107         uint32_t type;
 108         uint64_t config;
 109         char name[LTTNG_SYMBOL_NAME_LEN];
 110 };
 111
 112 /* Event/Channel context */
 113 struct lttng_event_context {
 114         enum lttng_event_context_type ctx;
 115         union {
 116                 struct lttng_event_perf_counter_ctx perf_counter;
 117         } u;
 118 };
 119
 120 /*
 121  * Event probe.
 122  *
 123  * Either addr is used or symbol_name and offset.
 124  */
 125 struct lttng_event_probe_attr {
 126         uint64_t addr;
 127
 128         uint64_t offset;
 129         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 130 };
 131
 132 /*
 133  * Function tracer
 134  */
 135 struct lttng_event_function_attr {
 136         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 137 };
 138
 139 /*
 140  * Generic lttng event
 141  */
 142 struct lttng_event {
 143         char name[LTTNG_SYMBOL_NAME_LEN];
 144         enum lttng_event_type type;
 145         uint32_t enabled;
 146         /* Per event type configuration */
 147         union {
 148                 struct lttng_event_probe_attr probe;
 149                 struct lttng_event_function_attr ftrace;
 150         } attr;
 151 };
 152
 153 /*
 154  * Tracer channel attributes. For both kernel and user-space.
 155  */
 156 struct lttng_channel_attr {
 157         int overwrite;                      /* 1: overwrite, 0: discard */
 158         uint64_t subbuf_size;               /* bytes */
 159         uint64_t num_subbuf;                /* power of 2 */
 160         unsigned int switch_timer_interval; /* usec */
 161         unsigned int read_timer_interval;   /* usec */
 162         enum lttng_event_output output;     /* splice, mmap */
 163 };
 164
 165 /*
 166  * Channel information structure. For both kernel and user-space.
 167  */
 168 struct lttng_channel {
 169         char name[NAME_MAX];
 170         uint32_t enabled;
 171         struct lttng_channel_attr attr;
 172 };
 173
 174 struct lttng_calibrate {
 175         enum lttng_calibrate_type type;
 176 };
 177
 178 /*
 179  * Basic session information.
 180  *
 181  * This is an 'output data' meaning that it only comes *from* the session
 182  * daemon *to* the lttng client. It's basically a 'human' representation of
 183  * tracing entities (here a session).
 184  */
 185 struct lttng_session {
 186         char name[NAME_MAX];
 187         /* The path where traces are written */
 188         char path[PATH_MAX];
 189 };
 190
 191 /*
 192  * Handle used as a context for commands.
 193  */
 194 struct lttng_handle {
 195         char session_name[NAME_MAX];
 196         struct lttng_domain domain;
 197 };
 198
 199 /*
 200  * Public LTTng control API
 201  *
 202  * For functions having a lttng domain type as parameter, if a bad value is
 203  * given, NO default is applied and an error is returned.
 204  *
 205  * On success, all functions of the API return 0 or the size of the allocated
 206  * array.
 207  *
 208  * On error, a negative value is returned being a specific lttng-tools error
 209  * code which can be humanly interpreted with lttng_get_readable_code(err).
 210  */
 211
 212 /*
 213  * Create an handle used as a context for every request made to the library.
 214  *
 215  * This handle contains the session name and lttng domain on which the command
 216  * will be executed on.
 217  */
 218 extern struct lttng_handle *lttng_create_handle(const char *session_name,
 219                 struct lttng_domain *domain);
 220
 221 /*
 222  * Destroy an handle. This will simply free(3) the data pointer returned by
 223  * lttng_create_handle() and rendering it unsuable.
 224  */
 225 extern void lttng_destroy_handle(struct lttng_handle *handle);
 226
 227 /*
 228  * Create tracing session using a name and a path where trace will be written.
 229  */
 230 extern int lttng_create_session(const char *name, const char *path);
 231
 232 /*
 233  * Destroy tracing session.
 234  *
 235  * The session will not be useable anymore, tracing will stopped for all
 236  * registered trace and tracing buffers will be flushed.
 237  */
 238 extern int lttng_destroy_session(struct lttng_handle *handle);
 239
 240 /*
 241  * List all tracing sessions.
 242  *
 243  * Return the size of the "lttng_session" array. Caller must free(3).
 244  */
 245 extern int lttng_list_sessions(struct lttng_session **sessions);
 246
 247 /*
 248  * List registered domain(s) of a session.
 249  *
 250  * Return the size of the "lttng_domain" array. Caller must free(3).
 251  */
 252 extern int lttng_list_domains(struct lttng_handle *handle,
 253                 struct lttng_domain **domains);
 254
 255 /*
 256  * List channel(s) of a session.
 257  *
 258  * Return the size of the "lttng_channel" array. Caller must free(3).
 259  */
 260 extern int lttng_list_channels(struct lttng_handle *handle,
 261                 struct lttng_channel **channels);
 262
 263 /*
 264  * List event(s) of a session channel.
 265  *
 266  * Return the size of the "lttng_event" array. Caller must free(3).
 267  */
 268 extern int lttng_list_events(struct lttng_handle *handle,
 269                 const char *channel_name, struct lttng_event **events);
 270
 271 /*
 272  * List available tracepoints of a specific lttng domain.
 273  *
 274  * Return the size of the "lttng_event" array. Caller must free(3).
 275  */
 276 extern int lttng_list_tracepoints(struct lttng_handle *handle,
 277                 struct lttng_event **events);
 278
 279 /*
 280  * Check if a session daemon is alive.
 281  */
 282 extern int lttng_session_daemon_alive(void);
 283
 284 /*
 285  * Set tracing group for the *current* flow of execution.
 286  */
 287 extern int lttng_set_tracing_group(const char *name);
 288
 289 /*
 290  * Return a human readable error message of a lttng-tools error code.
 291  *
 292  * Parameter MUST be a negative value or else you'll get a generic message.
 293  */
 294 extern const char *lttng_get_readable_code(int code);
 295
 296 /*
 297  * Start tracing for *all* registered trace (kernel and user-space).
 298  */
 299 extern int lttng_start_tracing(struct lttng_handle *handle);
 300
 301 /*
 302  * Stop tracing for *all* registered trace (kernel and user-space).
 303  */
 304 extern int lttng_stop_tracing(struct lttng_handle *handle);
 305
 306 /*
 307  * Add context to event for a specific channel.
 308  *
 309  * If event_name is NULL, the context is applied to all event of the channel.
 310  * If channel_name is NULL, a lookup of the event's channel is done.
 311  * If both are NULL, the context is applied on all events of all channels.
 312  */
 313 extern int lttng_add_context(struct lttng_handle *handle,
 314                 struct lttng_event_context *ctx, const char *event_name,
 315                 const char *channel_name);
 316
 317 /*
 318  * Create or enable a kernel event.
 319  *
 320  * If the event you are trying to enable does not exist, it will be created,
 321  * else it is enabled.
 322  *
 323  * If channel_name is NULL, the default channel is used (channel0).
 324  */
 325 extern int lttng_enable_event(struct lttng_handle *handle,
 326                 struct lttng_event *ev, const char *channel_name);
 327
 328 /*
 329  * Create or enable a kernel channel.
 330  *
 331  * If name is NULL, the default channel is enabled (channel0).
 332  */
 333 extern int lttng_enable_channel(struct lttng_handle *handle,
 334                 struct lttng_channel *chan);
 335
 336 /*
 337  * Disable kernel event.
 338  *
 339  * If channel_name is NULL, the default channel is used (channel0).
 340  */
 341 extern int lttng_disable_event(struct lttng_handle *handle,
 342                 const char *name, const char *channel_name);
 343
 344 /*
 345  * Disable kernel channel.
 346  *
 347  * If channel_name is NULL, the default channel is disabled (channel0).
 348  */
 349 extern int lttng_disable_channel(struct lttng_handle *handle,
 350                 const char *name);
 351
 352 /*
 353  * Calibrate LTTng overhead.
 354  */
 355 extern int lttng_calibrate(struct lttng_handle *handle,
 356                 struct lttng_calibrate *calibrate);
 357
 358 #endif /* _LTTNG_H */